1. Field of the Invention
This invention relates generally to polishing of ferroelectric materials and, more specifically to polishing of perovskite materials and still more specifically to polishing of barium strontium titanate.
2. Brief Description of the Prior Art
The surfaces of ferroelectric materials and specifically barium strontium titanate have been smoothed or planarized in the prior art by a fully mechanical process wherein the surface of the material was abraded using progessively less course polishing materials or grits to abrade the surface being polished. Such polishing continued until the desired smoothness or planarity was achieved.
A problem with the above described polishing method is demonstrated in FIG. 1 wherein there is shown a volume of barium strontium titanate 1 with a metal layer 3 thereon and an interface 5 between the metal and the BST. It can be seen that the surface of the BST 1 at and immediately below the interface 5 has numerous dislocations therein. Ferroelectric materials and specifically barium strontium titanate material with these dislocations, when used in uncooled focal plane arrays and the like, prevent the barium strontium titanate from obtaining optimal performance by causing depression of the dielectric properties and the responsivity of the material. This problem is enhanced as the thickness of the ferroelectric material decreases because the dislocation region becomes a greater percentage of the total volume.
It has been determined that these dislocations are caused by the mechanical abrading of the ferroelectric material surface. It is therefore apparent that the performance of optical arrays using ferroelectric materials will be improved if the surface of the material can be polished with a minimum of or no abrading at all. It has also been determined that polishing using typical polishing materials in a slurry or colloidal suspension, such as aluminum oxide (Al.sub.2 O.sub.3) or silicon dioxide, also produces dislocations on the ferroelectric material surface and can also modify the surface chemistry of the ferroelectric material.